1. Field of the Invention
The present invention relates to switching element driver integrated circuits (ICs) having insulation circuits such as photocouplers, and switching element driver devices equipped with the switching element driver IC.
2. Description of the Related Art
There are various types of switching element driver ICs equipped with one or more insulation circuits such as photocouplers. For example, there is a prior art document, “ACPL-330J, 1.5 Amp Output Current IGBT Gate Driver Optocoupler with Integrated (VCE) Desaturation Detection, UVLO, fault Feedback, Active Miller Clamp and Auto-Fault Reset, Data Sheet, AVAGO TECHNOLOGIES”, which has disclosed an insulated gate bipolar transistor (IGBT) gate driver IC.
The IGBT gate driver IC receives a driving signal and drives an IGBT on the basis of the received driving signal. Further, the IGBT gate driver IC detects occurrence of excess current and short circuit in the IGBT. When detecting occurrence of excess current and/or short circuit, generates and outputs a fault signal to outside devices. The IGBT gate driver IC is comprised of a first photocoupler (or a first optocoupler), a drive circuit, a detection circuit and a second photocoupler (or a second optocoupler).
The first photocoupler receives a driving signal transmitted from a device in a low voltage side, and transmits a signal to a high voltage side corresponding to the received driving signal, wherein the low voltage side is electrically insulated from the high voltage side in the first photocoupler. The driver circuit is electrically connected to the first photocoupler, and receives the signal transmitted from the first photocoupler. The driver circuit drives the IGBT on the basis of the received driving signal. The detection circuit detects occurrence of excess current and short circuit. The detection circuit outputs the detection result. Because the second photocoupler is electrically connected to the detection circuit, the second photocoupler receives the detection result transmitted from the detection circuit, and generates and transmits a fail signal corresponding to the received detection result, wherein the high voltage side is electrically insulated from the high voltage side in the second photocoupler.
On driving the IGBT as a target to be controlled and detected, it is necessary for each of the driver circuit and the detection circuit to have a gate voltage threshold value and an abnormality detection threshold value, etc. which are determined when the IGBT is turned on and off. In order to use various types of IGBT devices, an outside device determines such a gate voltage threshold value and an abnormality detection threshold value every IGBT device, and the IGBT gate driver IC uses those threshold values. However, this needs the high voltage side of the IGBT gate driver IC to have an increased number of terminals when compared with the number of terminals at the low voltage side thereof. When using driver circuits and detection circuits having high functionality, it is necessary for the IGBT gate driver IC to have the increased number of terminals at the high voltage side.
In order to adequately maintain the electrical insulation in the IGBT gate driver IC, it is necessary to arrange the terminals at the low voltage side and the high voltage side of the IGBT gate driver IC at a predetermined interval. If the number of the terminals at the high voltage side increases when compared with the number of the terminals at the low voltage side, an entire size of the IGBT gate driver IC therefore increases.